FIGURE 1-15

     This lateral view simply shows the 6 bones that contribute to the surface of the cranial cavity. In some regions the meningeal layer of the dura breaks away from the dural one to form tough, unyielding folds or partitions which partially subdivide the cranial cavity. Two of these - the falx cerebri and the tentorium cerebelli - are shown here. These partitions are important because when expanding lesions in the cranial cavity - blood or a tumor - displace brain tissue, it is often obliged to herniate around one of them.

     When the dural layers separate, as described above, they often enclose a network of venous sinuses. This is shown most clearly in this view, where the superior sagittal sinus. the inferior sagittal sinus and the superior petrosal sinus are labeled.